A typical surgical prosthesis includes a mesh made of a non-resorbable and biocompatible polymer. The mesh is composed of filaments that have interstices which permit tissue growth. The prosthesis also includes a sheet of polymer material having barrier properties and low adhesion to sensitive organs and tissues. This sheet is superimposed upon and joined to the mesh to form a stratified structure.
The prosthesis is implanted in a patient so that the mesh is in contact with the patients abdominal wall to reinforce it and stimulate the fibroplastic response. The sheet forming the barrier layer is placed in contact with the viscera of the patient to minimize adhesions.
A known prosthesis of this type is described in U.S. Pat. No. 6,270,530 to Eldridge et al. According to this patent, the mesh is joined to the sheet through a further intermediate mesh which is sewn to the first mesh on one side and is fused to the barrier sheet on the other through heat and pressure.
The intermediate mesh renders the structure of this prosthesis rather thick, rigid and heavy. As a consequence it is difficult to wrap the mesh in order to introduce it into the abdominal cavity using a trocar (or an instrument which, after creating the pneumoperitoneum, makes it possible to pass surgical instruments through holes made in the abdominal wall), restricting the possibilities for location. In addition to this the large quantity of material present in this prosthesis conflicts with the “less is more” concept expressed by U. Klinge and V. Schumpelick, in “Prosthetic Implants For Hernia Repair” BJS, Vol. 90(12), December 2003:1457-1458. According to this concept, the quantity and quality of the inflammatory response directly correlates with the quantity of implanted prosthetic material and the surface area in contact with host tissue. In particular, this inflammatory response causes the formation of scar tissue which covers the mesh, rendering it rigid and causing discomfort and pain to the patient. This is a serious drawback of the prior art mesh.
The object of this invention is therefore to provide a prosthesis which is improved in comparison with those described in the prior art.